Writing head producing a jet of ink



July 29, 1969 E. ASCOLI WRITING HEAD PRODUCING A JET OF INK Filed July6, 1967 2 Sheets-Sheet 1 0 M0 3 3 b d 8 J g 0 fi. Z m a r f WW a n 3 2 IH I 1|ll| J H 28 9 4 (I 4 5 5 H INVENTOR ENzo flue/4 BY W ATTORNEY July29, 1969 Filed July 6, 1967 E. ASCOLI WRITING HEAD PRODUCING A JET OFINK 2 Sheets-Sheet 2 INVENTOR ATTORNEY United States Patent 3,458,761WRITING HEAD PRODUCING A JET 0F INK Enzo Ascoli, Lausanne, Switzerland,assignor to Paillard S.A., Vaud, Switzerland, a company of SwitzerlandFiled July 6, 1967, Ser. No. 651,457 Claims priority, applicationSwitzerland, Feb. 13, 1967,

2,088/ 67 Int. Cl. G01d 15/16, 15/18 U.S. Cl. 317-3 3 Claims ABSTRACT OFTHE DISCLOSURE An electrically controlled writing head, wherein the samelongitudinal fraction of the jet of ink is subjected simultaneously tothe action of a pair of horizontal deflecting electrodes and of a pairof vertical deflecting elec trodes. Said electrodes are constituted byplates arranged in pairs interengaging each other as provided by thenotching of their cooperating edges perpendicular to each other and tothe axis of the jet.

Background of the invention Writing heads producing a jet of ink arealready known which include a body carrying a tube forming a nozzle forthe jet of ink and jet-deflecting electrodes located to either side ofthe axis of said tube.

In such writing heads, it is of interest to reduce its bulk as much aspossible and to draw faithfully the character of which the outline isdefined by the voltages applied to the deflecting electrodes.

Summary of the invention The present invention has for its object meansreducing substantially the length of the writing head and chieflycutting out any deformation of the character to be drawn, whichdeformation is ascribable to the duration of progression of the jet ofink as it passe between the first pair of electrodes and then betweenthe second pair, in the case where said two pairs of electrodes arelocated in sequence along the path of the jet of ink.

As a matter of fact, duringthe progression of the jet from one pair ofelectrodes to the next, the deflecting voltage applied to the secondpair can be modified and consequently the phase relationship between thehorizontal and vertical deflecting voltages would no longer remainunaltered.

The present invention has for its object a reading head projecting a jetof ink, of the type including a body'carrying a tube forming anozzle forthe jet'of ink and jet deflecting electrodes arranged pairwise to eitherside of the tube axis. This invention consists in that the electrodesare constituted by similar plates provided each with two notches alongone edge so that the notched sections of the two plates serving forvertical deflection engage without any direct contact therewith, thenotched sections of the two plates serving for horizontal deflection.Thus, all

deflecting electrodes extend in registry with the same por- I FIGS. 2and 3 are transverse cross-sections through lines II--II and III-III ofFIG. 1. 7

FIG. 4 is a perspective view of the electrode system.

, Description of the preferred embodiment.

The reading head illustrated includes a metal body 1 of which thecylindrical section 2 serves as a support for 3,458,761 Patented July29, 1969 a coaxial bell-shaped member 3 of insulating material. Saidbell-shaped member is merely slid over said cylindrical section 2 whichis provided with longitudinal slots 4 adapted to increase itselasticity. The bell-shaped member 3 may be obtained through molding andit includes a transverse partition 5 provided with an annular series ofopenings 6 and rigid with a sleeve-shaped coaxial member 7. Saidsleeve-shaped member 7 forms a unit with the bell-shaped member 3 andmay be cast for instance therewith out of a synthetic material such asthat sold under the registered trade name nylon. The sleeve 7 serves asa support for a metal annulus 8 inside which is set a tube 9 forming anozzle projecting the jet of ink. The ink is fed to the tube 9 through ayielding pipe 10.

The body 1 carries in its medial section a transverse annular partitionor wall 11 provided in its middle and in registry with the tube 9 withan opening 12 the edges of which are sharp.

The end of the body 1 opposed to its cylindrical section 2 forms fourlongitudinal projections 13, 14, 15, 16 of which the inwardly facingsurfaces are tapered at 17. Said tappings 17 allow screwing inside thebody 1, an outwardly projecting terminal metal member 18 adapted toclamp in position outside the body 1 a metal ring 19, a securing plug 20and two rings of insulating material 21 and 22 in contactingrelationship with a peripheral shoulder 23 provided on the outer surfaceof the body 1.

The two rings 21 and 22 serve as carriers for four plates 24, 24', 2 5,25 forming the electrodes deflecting the jet of ink projected out of thetube 9 through the opening 12 in the annular partition 11. The surfacesfacing each other on the rings 21 and 22 are provided with grooves 21and 22 respectively, which serve as guides for the electrode plates. Asillustrated in FIGS. 1 and 3, the plates 24 and 24 are provided eachwith two notches a, whereas the plates 25 and 25 show each two notchesb. The plates 24, 24, 25, 25 are furthermore given substantially thesame shape and are arranged'pairwise at right angles and in oppositerelationship. Said arrangement allows interengaging said plates'withoutany electric contact between them, the plates 24,24"1ying in twovertical parallel planes and the plates 25, 25 in two horizontal planes.Said interengaging plates occupy thu a minimum space in a directionparallel with the axis of the tube 9. Thus,'the particles of ink passsimultaneously between the horizontal deflecting platesand the verticaldeflecting plates. This leads to an important advantage since,if thepairs of deflecting plates were arranged in sequence along the path ofthe jet of ink, this would lead to a'deformation of the character drawnby it a a consequence of the time required for the progression oftheparticles from one pair ofplates to the next. The structure disclosedthus cutsout completely said'drawback. It should be mentioned that nopart of insulated material is apparent to view from any point ofobservation located at theend of the nozzle tube 9. As a matter of fact,said end of'the tube 9 cannot possibly see the bell-shaped member 3 madeof insulating material, which member is concealed by the inner annulus 8and the outer cylindrical section 2. Similarly, the two insulating rings21 and 22 are concealed by the annular portition 11. Thus, the electricfield extending between the tube 9 and partition 11 is not subjected tothe action of the electric loads which may be carried by the parts ofinsulating material as provided for instance by a capacitory influence.

In order to reduce as much as possible any parasitic action as aconsequence of the static loads carried by the insulating parts, the tworings 21 and '22 are spaced with reference to the path followed by thejet of ink by the projections 13 to 16 on the support 2 and also by theintermediate projections 26 (FIG. 3) inserted between the formerprojections. Thus, the jet of ink is protected to a maximum extentagainst any parasitic action ascribable to the static loads possiblycarried by the insulating parts. Furthermore, the sole parts of the jetof ink which might be subjected to some slight action of the staticloads carried by the rings 20 and 22 extend between the opening 12 andthe entrance of the jet into the passage defined by the electrodes andalso between the output of said passage and entrance of the openings 27defined by the terminal metal member 18.

It should be remarked that the plates 24, 24', 25, 25' project beyondthe outer periphery of the rings 21 and 22 so that it is possible toweld thereto conducting wires adapted to give said plates the desiredinstantaneous voltage.

The voltage applied to the tube 9 is transmitted either by theconductive ink or else by a metal lead which may, as a matter of fact, binserted inside the yielding pipe 10.

As soon as the ditference in voltage between the partition 11 which isgenerally grounded and the tube 9 is sufliciently high, the ink escapingout of said tube forms a jet constituted by a succession of droplets.Said jet passing between the deflecting electrodes is shifted under theaction of the voltages applied to said deflecting electrodes.

Preferably, the carrier parts made of metal, that is the parts 2, 20 and18 are subjected to the same voltage as the support carrying the surfaceto be written over. Consequently, the electric field between the opening27 in the terminal member 18 and said surface showing the point ofimpact for the jet of ink is equal to zero and the path of the jet ofink can therefore no longer be modified between the output of thewriting head and said point of impact onto the writing surface.

The extremely small ink droplets forming the secondary jet escape withina cone the apical angle of which is large and are arrested by thepartition 11. The latter is polished and the edge of the opening 12therein is very sharp so that the droplets forming the secondary jetcannot collect on such a sharp cutting edge by reason of the surfacepressure of the ink droplets. Furthermore, the sharp edge of the opening12 merges into the surface of the partition 11 facing the tube 9 along aconvex annular surface 11a which is also polished so as to further thecoalescence of the extremely small ink droplets which may settle on saidannular surface. Said droplets form thus a continuous annular sheet ofink which flows steadily towards anoutput port opening into thedepending tube '28 as furthered by a verticalgroove 29 extending betweenthe convex surface 11a and said output port.

The above-described writing head shows numerous advantages over thoseproposed hitherto. As a matter of p the like objectionable actions.

By reason of the shield formed by the metal parts carrying the head, theelectricfields inside said head remain valways uniform and their valuesare well-defined. Said fields can be deformed neither by. outerparasiticfields, nor under the action of the, static loads which may collect onthe insulating parts.

The openings 6 formed in the partition 5 allow air to enter the writinghead so as to replace the air escaping through the opening '27 and whichis carried along by" the moving jet of ink; 'Thus, the air pressureinside the head remains substantially constanttwhich is essential with aview to obtaining a clean writing.

be system of carrierparts isrigid with the securing lug 20 as providedby the mere screwing of the terminal member 18 inside the threads 17 cutin thelongitudinal projections 13 to 16. To this end, the terminalmember 18 is provided along its outer edge with a slot 29' adapted to beengaged by a screw-driver. Furthermore, the insulating bell-shapedmember 3 rigid with the annulus 8 and tube 9 may be removed through amere sliding over the cylindrical section 2 of the body 1 which allowsinspecting and cleaning easily said tube 9.

I claim: v v 1. In a writing head comprising a nozzle through which ajet of ink is projected, the provision of a first pair of deflectingelectrode plates provided along one edge with two notches spaced by thesame amount and extending in transverse registry with the location of apredetermined section of the jet projected out of the nozzle and asecond pair of deflecting electrodes extending perpendicularly to theelectrodes of the first pair in transverse registry with the samelocation and one edge of which engages the corresponding notches in theelectrode plates without any contact between the plates of the twopairs.

' 2. A writing head as claimed in claim 1, wherein the electrode platesof the'second pair are also provided along their said one edges with twonotches spaced by the same amount, the notched sections of the plates ofsaid second pair engaging the notches in the plates of the first pair.

'3. A writing head as claimedin claim 1, comprising two annular ringssurrounding the location of said predetermined section of the jet andprovided in their cooperating adjacent surfaces with two spaced groovesin one direction and with two further spaced grooves perpendicular tothe first-mentioned spaced grooves for engagement respectively by theedge of the corresponding electrode plates perpendicular to the said oneedges, in the plates of the first pair.

References Cited UNITED -STATES PATENTS:

LEE T. l-IIX, Primary Examiner V

